Most printing systems in use today utilize printing plates or cylinders which are engraved or photochemically processed to create an image thereon. Ink is then deposited on the plate or cylinder and the ink is thereafter transferred to a substrate, such as paper. In a conventional printing press, a number of pages are printed on a sheet of paper to form a signature which is then folded and assembled with other signatures. The assembled signatures are then bound, trimmed and finished by finishing apparatus to produce finished books, such as magazines, catalogs or any other printed and bound matter.
Often, there is a need to produce different versions of books and/or customized books within a single press run. For example, it may be desirable to produce a number of standard books together with a number of books having additional and/or different signatures or pages therein. Also, it may be necessary or desirable to provide customized information in the form of an address label, personalized information or the like on the inside or outside of finished books. In either case, conventional printing systems are not easily adaptable to produce books of these types.
A printing system which has the ability to produce differing book versions and/or books with customized information is disclosed in Riley U.S. Pat. No. 4,121,818, assigned to the assignee of the instant application. The printing system includes a number of packer boxes disposed adjacent a binding chain wherein each packer box stores a plurality of signatures. A control is included for controlling the packer boxes to selectively feed signatures onto chain spaces of the binding chain so that books of varying content can be produced. Customized information can be printed on the signatures by means of an ink jet printer which is selectively operated by the control. Other types of customization can be effectuated, such as by inserting or onserting cards or the like.
Other systems for producing customized books are disclosed in Abrams et al. U.S. Pat. No. 3,899,165, Wong et al. U.S. Pat. Nos. 4,500,083 and 4,674,052, Wong U.S. Pat. No. Re 32,690 and Berger et al. U.S. Pat. Nos. 4,768,766 and 4,789,147.
Image manipulating systems have been developed which permit gathering of images in an office or home environment. For example, conventional word processing programs, such as Microsoft.RTM. Word.RTM., WordPerfect.RTM. and the like, permit a user to import images into a page and also allow a user to command which pages of a document to print. In addition, macros (i.e., a sequence of commands) can be assembled and executed within these programs which can allow printing of particular document pages in a certain order. Still further, most word processing programs have merge capability wherein a customized image is merged with other standardized information and printed or displayed. As one example, customized information in the form of addressee and address information may be merged with standardized return address information and printed on a series of envelopes.
A different image gathering capability provided by CAD (computer aided design) software, sometimes referred to as "layering," involves the creation and storage of a base page and one or more layer pages. A user can issue commands to display or print the base page and one or more of the layer pages simultaneously atop one another to achieve an effect similar to the overlay of transparencies so that a composite page appearance results.
While the foregoing image manipulating systems allow some image gathering capability, none is effective to assist in the rapid production of different book versions. Of course, CAD systems are primarily designed for line art and not text or graphic images, and hence are of only limited use. Further, if one were to use word processing software to produce book versions it would be necessary to issue commands to separately print the pages of each book version just before such version is to be produced. That is, a user would have to create and store pages to be included in a first book version and then command the software to print as many copies of the first version as are needed. Thereafter, the user would have to recall the pages of the first version from memory, edit and store the pages to create pages to be included in a second book version and then command the system to print the required number of books of the second version. Similar steps would have to be undertaken for each other book version to be produced. Alternatively, the pages of the different book versions could be created and stored and thereafter printed together. In either event, where many book versions are to be produced, such a process would be quite time-consuming. In addition, image importation and merge routines provided as a part of word processing software are adapted for use on a sub-page basis only and hence are of only limited usefulness in the book production environment. Still further, data manipulated by word processing software are largely (if not entirely) in symbolic format. As a result, data to be displayed or printed must be first rasterized by a raster image processor (RIP), which utilizes complex and time-consuming computational routines which further increase production time to an economically impractical level.
Recently, new printing systems have been developed, called "demand printers," which are capable of high speed printing of images from electronic representations thereof. The demand printer produces high quality color (or black and white) images using a set of fusible toners in an electrophotographic process. More particularly, a web of paper is passed adjacent a series of drums, each of which has been electrostatically charged according to an image pattern for a particular color to be applied to the web. The charge is transferred to the paper and an oppositely charged toner of the proper color is brought into contact with the paper. The oppositely charged web and toner attract so that the toner is held on the paper as other colors are applied thereto. The toners and paper are thereafter heated to fuse the toners to the paper to produce the final image. The web is then cut into sheets (or "forms") and the forms are further processed as needed to produce a final product.
Unlike conventional presses which utilize engraved or photochemically prepared plates or cylinders, demand printers are capable of rapidly printing high quality images of differing content owing to the fact that the images are produced by an electrophotographic process. That is, instead of the need to replate and re-engrave a gravure cylinder when a different image is to be printed therewith, it is only necessary to change the charge applied to the drums of the printer in order to make such change. Thus, different images can be printed by the same printer without significant delays. This advantage makes the demand printer desirable for use in certain production environments.
Warmus et al. U.S. patent application Ser. No. 08/478,397, entitled "Variable Imaging Using An Electronic Press" discloses an apparatus and method for controlling an electronic press so that fixed and variable information may be printed in a simple and effective manner. More particularly, first and second sets of template data representing associated first and second template pages, respectively, are developed. Each set of template data includes master data representing fixed information and area data representing an area of a page for variable information. A database is also developed having a number of entries each of which represents variable information. The printer is operated in accordance with the sets of template data and the entries in the database such that the first and second template pages are displayed with selected variable information.
The Warmus et al. apparatus and method generates a page definition language representation of each single page and thereafter generates a page definition language representation of each imposed flat, i.e., each side of a piece of paper to be printed with two or more pages. Such a procedure can be computationally expensive and may limit productivity.